PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
June 2019
409
by
Clifford J. Mugnier, CP, CMS, FASPRS
T
he area now known as the Swiss
Confederation was occupied by Helvetians
who were conquered by the Romans; the
southwest was invaded by Burgundians, and the
northeast was invaded by Alamanni. In 1291 the
Forest Cantons, or provinces of Uri, Schwyz, and
Unterwalden, formed an anti-Hapsburg league
that became the nucleus of the Confederation.
The perpetual neutrality of Switzerland was
guaranteed by international agreement in 1815 at
the Congress of Vienna and again in 1919 by the
Treaty of Versailles. Its present constitution was
adopted in 1874. The highest peak of this Federal
Republic is Monte Rosa at 4,638 m (15,217 ft). The
Swiss Confederation shares borders with France,
Germany, Italy, Austria, and the Principality of
Liechtenstein.
G. H. Dufour, later to become a general, founded the Eid-
genößisches TopographischesBureau (Topographical Bureau)
in Geneva in 1838. Dufour decided to use the “carte du jour”
projection of Europe for the time which was the ubiquitous
Ellipsoidal Bonne originally used for topographic mapping by
Cassini himself during the Napoleonic Campaigns. The grid
used for this Ellipsoidal Bonne has a Latitude of Origin (
j
o
) = 46° 57´ 06.02˝ N, a Central Meridian (
l
o
) = 7° 26´ 24.75˝
East of Greenwich (5° 06´ 10.80˝ East of Paris), a False East-
ing of 600 km and a False Northing of 200 km. The Berne Ob-
servatory Datum was circa 1840, and the ellipsoid used was
the Schmidt 1831 where a = 6,376,804 m, and
1
/
f
= 302.02.
Although my notes show a false origin for this old grid, I sus-
pect that the original use was with the traditional quadrant
system. The false origin probably crept into use as the base
was updated after the Rosenmund System was introduced in
the 20
th
century. From 1845 to 1864, the publication of the
first accurate map, known as the “Dufour Map,” covering the
whole of Switzerland was performed at the scale of 1:100,000;
THE
The Grids & Datums column has completed an exploration of
every country on the Earth. For those who did not get to enjoy this
world tour the first time,
PE&RS
is reprinting prior articles from
the column. This month’s article on the Swiss Confederation was
originally printed in 2001 but contains updates to their coordinate
system since then.
the slopes were shown by hatchures. By this time, the classi-
cal triangulation of Switzerland comprised 40 triangles that
had been observed with Kern instruments, and the average
error of a figure was 0.86 arc seconds. The Swiss triangu-
lation calculations were based on the Bessel 1841 ellipsoid
after 1863 where
a
= 6,377,397.155 m, and
1
/
f
= 299.1528. The
office was transferred to Berne in 1868, and the publication of
the original surveys at 1:25,000 (Swiss Central Plains) and at
1:50,000 (Alps) with contours was performed from 1870-1916.
The Old Berne Observatory Datum of 1898 published an As-
tronomical Latitude (Φ
o
) = 46° 57´ 08.66˝ N, based on obser-
vations executed by E. Plant amour in 1875 and an Astro-
nomical Longitude (Λ
o
) = 7° 26´ 22.5˝ East of Greenwich. The
defining azimuth to station Rötifluh was (
α
o
) = 11° 12´ 05.24˝.
The ellipsoid height and deflection of the vertical are not de-
fined and therefor are forced to zero at the origin.
Photogrammetric Engineering & Remote Sensing
Vol. 85, No. 6, June 2019, pp. 409–410.
0099-1112/19/409–410
© 2019 American Society for Photogrammetry
and Remote Sensing
doi: 10.14358/PERS.85.6.410
